1. Field of the Invention
The present invention relates to a touch screen and a method for detecting touches and the touch location on the touch screen.
2. Description of the Related Arts
Modern electronic devices often have touch sensors to receive input data. There are a variety of types of touch sensor applications, such as touch screens, touch buttons, touch switches, touch scroll bars, and the like. Touch sensors have a variety of types, such as resistive type, capacitive type, and electromagnetic type. A capacitive touch screen is coated with a transparent conductive material, typically Indium Tin Oxide (ITO), that conducts continuous electrical current across a sensor. The sensor exhibits a precisely controlled field of stored electrons in both the horizontal and vertical axes of a display to achieve capacitance. The human body is also an electrical device which has stored electrons and therefore also exhibits capacitance. When the sensor's normal capacitance field (its reference state) is altered by another capacitance field, e.g., by the touch with someone's finger, capacitive type touch sensors measure the resultant distortion in the characteristics of the reference field and send the information about the touch event to the touch screen controller for mathematical processing. There are a variety of types of capacitive touch sensors, including Sigma-Delta modulators (also known as capacitance-to-digital converters (CDCs)), charge transfer type capacitive touch sensors, and relaxation oscillator type capacitive touch sensors.
Conventional touch screens typically require multiple layers of ITO to detect multiple touches on the touch screen. Some conventional touch screens may use a single ITO layer, but they are not capable of determining the location of multiple simultaneous touches due to the way the single ITO layer is disposed on the touch screen.